Adjustable fin system

ABSTRACT

An adjustable fin for use on a surfboard, the adjustable fin comprising: a base which comprises a mounting means for mounting the adjustable fin to a surfboard, and a member extending in a direction contrary to the mounting means. The adjustable fin further comprises a fin section comprising two outer fin surfaces which meet at a leading edge and a trailing edge; an underside surface comprising an opening to an internal cavity, the internal cavity configured to house the member and enable slidable movement of the member in a direction towards the leading edge or the trailing edge; and a locking means that is manipulate and which projects into the internal cavity, wherein the locking means can releasably couple to the member at one of two or more locking positions thereby preventing slidable movement of the member. The fin section can be adjusted relative to the base by manipulating the locking means to uncouple the locking means from the member at a first locking position, slidably move the member through the internal cavity, and releasably couple the locking means to the member at a second locking position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 15/110,392 having aninternational filing date of 14 May 2015, now allowed, which is a U.S.National Phase Application of International Application No.PCT/AU2015/050241 having an international filing date of 14 May 2015,which claims the benefit of earlier filing date and right of priority toAustralian Patent Application Nos. 2014901808, filed on 15 May 2014;2015901152, filed on 30 Mar. 2015; and 2015901529, filed on 29 Apr.2015. The contents of the above patent applications are incorporated byreference herein in their entirety.

TECHNICAL FIELD

The present invention relates to an adjustable fin for a surfboard. Moreparticularly, the invention relates to a surfboard fin or dual surfboardfin that can be adjusted by hand without the need for any tools.

BACKGROUND ART

The following discussion of the background art is intended to facilitatean understanding of the present invention only. The discussion is not anacknowledgement or admission that any of the material referred to is orwas part of the common general knowledge as at the priority date of theapplication.

A surfboard, stand-up paddleboard (SUP), or similar type of board foruse in water sports and other activities can be viewed in one sense as asummation of hydrodynamic surfaces. The surface of the bottom of theboard in contact with water generates lift and affects speed. Moreimportantly though, it is the fins working in collaboration with railand bottom contour that most influence the feel of the board whenchanging direction. Since the form shape of surfboards including therails and bottom surface has undergone finer and finer adjustments overthe past few decades, the largest gains that can still be made to aboard's performance is in fin modification.

Predominant factors that influence the effect of the fins include (i)foil shape, and the curve from leading to trailing edge as it changesfrom base to tip; (ii) template shape, which is the combination ofdepth, width, and rake that make up the profile of the fin; (iii)stability and flex, which can depend on the materials from which a finis made; and (iv) fin placement, which comprises tow and camber of thefins, the distance between the fins, and the distance of the fins fromthe rear of the board.

Foils comprise surfaces which affect lift and drag. Where one surface ofa foil is curved and the other, predominantly flat (a ‘flat foil’), ittakes less effort (drag) for liquid to flow past the flat surface as thepath of least resistance than the curved surface. As a result, morewater will flow past the flat surface of the foil creating an area ofhigh pressure. Conversely, an area of low pressure is created adjacentto the curved surface of the foil. This difference in pressure createslift towards the curved side of the foil. The more curve a foil has, themore drag it induces over the curved surface which means that a foilwith greater curvature will have more lift at lower speeds. The problemis at higher speeds that additional drag will develop turbulence andstall the flow across the foil. Side fins on a surfboard are usuallyflat foils which are oriented with the flat face of the foil facingtowards the centre or stringer of the board. The resulting pressuredifferential assists to pull the board fins and rail of the surfboarddown into the water. Therefore, thicker, more curved foils are preferredby surfers for slow waves, and flatter, finer foils for faster waves.

Template shape affects stability and control. As an example, fins thatare deeper, with a wider base and more rake provide greater stabilityand control as a result of a relatively large surface area. However,more surface area causes greater drag and slows a board down. As ageneralisation known amongst surfers, fins with a greater surface areaare more preferred for steep and heavy waves, choppy and irregularconditions, for heavier surfers, and/or surfers with a flowing style.Alternatively, fins with less surface area are more preferred forsloped, clean and glassy waves, for lighter surfers, and/or surfers thatexercise extreme and radical manoeuvres.

The flex of a surfboard fin can affect stability in turns. For example,a flexible tip on a fin can dampen or smooth out some of the bite when asurfer changes direction on a surf board. But a stable fin base iscrucial to prevent or minimise turbulence which can generate drag anddisturb the lift causing loss of fin control, making the board slow andout of control. Less flex can make turns more off a pivot.

‘Toe’ can be considered in terms of the angle the base of the side finsare pointed in towards the centre of the board relative to the leadingedge and trailing edge at the base. ‘Cant’ can be considered in terms ofthe angle the body of a fin is set at relative to the bottom surface ofthe board in a plane perpendicular to the direction of the stringer.Both toe and cant affect the ‘angle of attack’ of fin foils in theirmovement through the water. A greater angle forces more water flowaround the outside curved surface of the foil at lower speeds making iteasier to initiate turns on slower waves. However, too much angle athigher speeds increases turbulence and drag slowing down the board.

Since the introduction of removable fins about two decades ago by FCS®,there has been a greater interest from surfers and particularlyprofessional surfers in fin placement in addition to the other factorsdescribed above. While fin placement is often left to convention, forexample, with many board shapers following the benchmark for approximatelocation set by Simon Anderson more than thirty years ago, many otherboard shapers have their personal preference for each surf board modelthey shape. There are, however, subtle differences in most boards and inall riders. An adjustment of the position of a fin as small as a 4 mmfin movement fore or aft in either or both the centre fin or side finscan have a profound effect on the performance of a board, similar to achange of fin size or template. In general terms, moving a fin towardsthe rear of the board will stiffen the board, allowing it to handlegreater speed and irregular water conditions. Moving a fin forward willloosen the board allowing it to turn on a tighter radius for easierchanges in direction, and is preferable in glassy water conditions andshort beach surf breaks.

Removable fin arrangements and systems have therefore been designed,with some available for purchase, which allow a surfer to adjust theposition of a fin on their surfboard, and in some cases, even the towand cant of the fin. However, these removable and adjustable finarrangements commonly attach to their own unique and custom fin box orplug requiring a new board or modifications to an existing board. Manyof these adjustable fin arrangements also require tools to be carried bythe surfer to adjust the position of the fins on the board. As a result,there has been a relatively small uptake of these adjustable finarrangements by the millions of surfers and other board riders aroundthe world.

SUMMARY OF THE INVENTION

First Aspect

In a first aspect, the invention provides an adjustable fin for use on asurfboard, the adjustable fin comprising:

a base comprising:

-   -   a mounting means for mounting the adjustable fin to a surfboard;        and    -   a member extending in a direction contrary to the mounting        means;

a fin section comprising:

-   -   two outer fin surfaces which meet at a leading edge and a        trailing edge;    -   an underside surface comprising an opening to an internal        cavity, the internal cavity configured to house the member and        enable slidable movement of the member in a direction towards        the leading edge or the trailing edge; and    -   a locking means that is manipulable and which projects into the        internal cavity, wherein the locking means can releasably couple        to the member at one of two or more locking positions thereby        preventing slidable movement of the member;        wherein the fin section can be adjusted relative to the base by        manipulating the locking means to uncouple the locking means        from the member at a first locking position, slidably move the        member through the internal cavity, and releasably couple the        locking means to the member at a second locking position.

In a preferred embodiment, the locking means is biased towards beingreleasably coupled to the member at a locking position.

In another preferred embodiment, the locking means is manipulable froman outer fin surface. The locking means preferably comprises a button atan outer fin surface for manipulating the locking means, and depressingthe button uncouples the locking means from the member. Releasing thebutton preferably releasably couples the locking means to the member ata locking position.

The member is preferably substantially planar, comprising a flat orsubstantially flat surface. Preferably, the planar member isapproximately 1 mm thick. In a preferred embodiment, the membercomprises a hole, and the hole is configured to receive the lockingmeans. Preferably, the locking means releasably couples to the member atany one of two or more locking positions in the hole. More preferably,the locking means passes through the hole which maintains engagementbetween the base and the fin section.

In a preferred embodiment, the hole in the member comprises one or moreteeth, wherein either side of a tooth can be a valley, and a valley canform a locking position. The peak of the teeth may be pointed or roundedin shape. Preferably, the one or more teeth are aligned substantiallyparallel to the underside surface, and point in a direction contrary tothe underside surface. That is, the peak of the one or more teethpreferably point in a direction contrary to the underside surface andmounting means.

At least a portion of the locking means is preferably received at alocking position in a valley thereby coupling the locking means to themember. Depressing the button preferably aligns the teeth with a slot inthe locking means, the slot having a width through which the teeth mayslidably move, therein uncoupling the locking means from the member andenabling slidable movement of the teeth through the slot. An upperportion of the locking means preferably extends above the valley and theheight of the peaks of the adjacent teeth, and a lower portion of thelocking means is positioned within the valley. Preferably the lowerportion and only part of the upper portion of the locking meanscomprises the slot. More preferably, the button comprises the slot.Therefore, when the locking means has been uncoupled from the memberwhen the button has been depressed, the slot aligns with the teethenabling slidable movement of the teeth through the slot. Preferably,releasing the button when the locking means is aligned with a valleyreleasably couples the locking means to the member, wherein the valleycomprises a locking position.

A surface of the undepressed button is preferably aligned flush with theouter fin surface. That surface comprises the top of the button which auser can depress to manipulate the locking means. As the button isaligned flush with the outer fin surface, no additional drag ispreferably created adjacent to that outer fin surface. The button may beconstructed from a variety of materials. Preferably, the button isconstructed from the same material as the fin section.

A user can preferably apply sufficient manual force by hand to depressthe button and adjust the position of the fin section relative to thebase when the adjustable fin is mounted to a surfboard.

Second Aspect

In a second aspect, the invention provides an adjustable fin for use ona surfboard, the adjustable fin comprising:

a base comprising:

-   -   a mounting means for mounting the adjustable fin to a surfboard;        and    -   a member extending in a direction contrary to the mounting        means, the member comprising an extension;

a fin section comprising:

-   -   two outer fin surfaces which meet at a leading edge and a        trailing edge;    -   an underside surface comprising an opening to an internal        cavity, the internal cavity configured to house the member and        enable slidable movement of the member in a direction towards        the leading edge or the trailing edge;    -   a channel in the internal cavity configured to house the        extension to maintain engagement between the base and the fin        section, and enable slidable movement of the extension in a        direction towards the leading edge or the trailing edge,    -   the internal cavity containing a resiliently deformable material        that restrains movement of one or both of the member and the        extension within the internal cavity;        wherein when an application of manual force on the fin section        in a direction away from the base overcomes the restrained        movement of one or both of the member and the extension by the        resiliently deformable material, the fin section may be slidably        moved relative to the base in a direction towards the leading        edge or the trailing edge.

The resiliently deformable material is preferably an elastic polymer.More preferably, the resiliently deformable material is neoprene. In onenon-limiting example, the neoprene is of similar or the same resilienceand deformability as neoprene used in other commercially available surfproducts such as surfboard leashes or wetsuits. Part or all of theresiliently deformable material in the adjustable fin of the inventionmay be replaceable.

In a preferred embodiment, the member extending from the base ispreferably substantially planar, or more preferably comprises asubstantially planar plate. Preferably, the planar member isapproximately 1 mm thick. This can allow the construction of arelatively thin adjustable fin of the invention which is preferable forreducing fin drag. The internal cavity of the fin section preferablycomprises a slot configured to house the substantially planar member andthrough which the member can slidably move.

The extension preferably comprises a flange. The flange is preferablyattached to a planar portion of the member. More preferably, theposition of the flange is substantially perpendicular to a planarportion of the member and substantially parallel to the undersidesurface. The flange is preferably positioned on the member approximatelyhalf-way between where the member joins the mounting means and theopposite end of the member. Preferably, the flange is approximately 1 mmthick. The channel in the internal cavity is preferably configured tohouse the flange and enable slidable movement of the flange through thechannel.

In an embodiment of the invention, the resiliently deformable materialis located in the internal cavity and restrains movement of the memberin the internal cavity. In a preferred embodiment, the channel containsthe resiliently deformable material restraining movement of theextension in the channel. Even more preferably, the extension is aflange on a planar member and the resiliently deformable material issituated between the flange and the surface of the channel nearest tothe underside surface. The resiliently deformable material preferablyholds the flange with elastic pressure against the surface of thechannel furthest from the underside surface and as a result offrictional force, holds the member and base in position relative to thefin section. The elastic pressure is preferably sufficient to preventmovement of the fin section relative to the base when the adjustable finis attached to a surfboard and the surfboard is in normal use. When theadjustable fin is mounted to a surfboard, the underside surfacepreferably abuts or is aligned with the outside surface of thesurfboard.

In a preferred embodiment of this second aspect of the invention, a userof the adjustable fin can apply sufficient manual force by hand toadjust the position of the fin section relative to the base in adirection towards the leading edge or the trailing edge. When theadjustable fin is mounted to a surfboard, the user of the surfboard canadjust the fin by hand whether on land or in water, without anyrequirement for tools or any other equipment, to move the position ofthe fin section, relative to the base, towards the front or rear of thesurfboard. Upon removal of the manual force, the resiliently deformablematerial again restrains movement of one or both of the member and theextension within the internal cavity, therein holding the fin section inthe recently adjusted position and preferably preventing movement of thefin section relative to the base when the adjustable fin is attached toa surfboard and the surfboard is in normal use.

Sufficient manual force as described herein comprises force able toovercome the elastic pressure of the resiliently deformable material andallow slidable movement of the member and extension within the internalcavity and channel, respectively, and therefore adjustment of theposition of the fin section relative to the base. More preferably,sufficient manual force as described herein comprises force against theelastic pressure of the resiliently deformable material that is able toseparate the extension from the surface of the channel furthest from theunderside surface, allowing slidable movement of the extension throughthe channel.

The length of the channel will determine the distance the fin sectionmay be adjusted by slidable movement towards the leading edge or thetrailing edge, relative to the base. Preferably, the channel allows upto approximately 10 mm to 30 mm of movement of the fin section relativeto the base in a direction towards the leading edge or the trailingedge. More preferably, the channel allows up to approximately 20 mm ofmovement of the fin section relative to the base in a direction towardsthe leading edge or the trailing edge. The amount of slidable movementwill depend on the size and shape of the fin section which will limitthe length of the channel possible within the fin section. Upon removalof the sufficient manual force, the elastic pressure of the resilientlydeformable material will again force the extension against the surfaceof the channel furthest from the underside surface holding the positionof the fin section relative to the base in place by frictional force.Means for showing the user the position of the fin section relative tothe base are also within the scope of the invention, for example, toenable a user to adjust two or more fins on a board equally.

In a further embodiment of the invention, the member comprises one ormore teeth which can be received by teeth-shaped recesses in theinternal cavity. The teeth assist the resiliently deformable material byproviding an additional means to restrain movement of the member in theinternal cavity, and therefore the fin section relative to the base.Preferably, the adjustable fin of the invention comprises one or moreteeth at the end of the member furthest from the mounting means, saidteeth corresponding to recesses in the internal cavity that can receivethe teeth and assist to restrain movement of the member in the internalcavity. When applying sufficient manual force to adjust this embodimentof the adjustable fin, the application of sufficient manual force willfurther comprise movement of the fin section in a direction away fromthe base, against the elastic pressure of the resiliently deformablematerial, to dislocate the one or more teeth from the recesses to enableslidable movement of the member within the internal cavity, and theextension within the channel.

The teeth are preferably positioned at the end of the member proximal tothe trailing edge of the fin section, and the application of sufficientmanual force will further comprise movement of the fin section in adirection away from the base at the rear or trailing end of the finsection to dislocate the teeth from the recesses in the internal cavity.Upon removal of the sufficient manual force, the elastic pressure of theresiliently deformable material against the extension will force themovement of the fin section in a direction towards the base and recessesin the internal cavity can receive any adjacent teeth on the base. Thenumber and position of the teeth will determine the position the finsection may be adjusted to relative to the base.

Third Aspect

In a third aspect, the invention provides a dual fin comprising a finsection, a second fin section and a base, the base comprising a mountingmeans for attaching the dual fin to a surfboard.

In preferred embodiments of the third aspect of the invention, a secondfin section is attached to the fin section according to either the firstaspect of the adjustable fin of the invention or the second aspect ofthe adjustable fin of the invention, the second fin section comprisingtwo outer fin surfaces which meet at a leading edge and a trailing edge,and an underside surface.

The second fin section is preferably attached to the fin section by oneor more attachment means. Attachment means may, in some non-limitingexamples, comprise rods, plates, pins, bars, and/or be formed from aportion of either the fin section or the second fin section. Morepreferably, the one or more attachment means comprise one or more ribs.The one or more attachment means preferably preserve a minimum distancebetween the fin section and the second fin section of betweenapproximately 0.1 mm and 5 mm. The one or more attachment meanspreferably preserve a minimum distance between the fin section and thesecond fin section of between approximately 0.25 mm and 1.5 mm. The oneor more attachment means more preferably preserve a minimum distancebetween the fin section and the second fin section of approximately 1mm. The attachment means preferably reduce or remove any flutteringeffect on either fin section caused by water passing around and betweenthe fin section and the second fin section.

The second fin section is preferably positioned substantially parallelto the fin section and offset such that the leading edge of the secondfin section is not aligned with the leading edge of the fin section. Thefin section preferably comprises a flat foil having a substantially flatouter fin surface, and a curved outer fin surface. The second finsection also preferably comprises a flat foil having a substantiallyflat outer fin surface, and a curved outer fin surface. In a preferredembodiment, the substantially flat outer fin surface of the fin sectionand substantially flat outer fin surface of the second fin sectionsubstantially face the same direction, and the leading edge of the finsection is in a position forward of the leading edge of the second finsection. Preferably, the leading edge of the fin section is forward ofthe leading edge of the second fin section by approximately 5 mm to 25mm, and more preferably by approximately 10 mm.

The second fin section preferably comprises at least one passage throughwhich water can pass. The passage comprises an opening on each outer finsurface of the second fin section through which water can enter andexit. The passage preferably comprises an opening on the substantiallyflat outer fin surface, and an opening on the curved outer fin surface,and the opening on the curved outer fin surface is located between thetrailing edge of the second fin section and the minimum distance betweenthe fin section and the second fin section. Preferably, the opening ofthe passage on the substantially flat outer fin surface of the secondfin section is located closer to the leading edge of the second finsection than the opening of the passage on the curved outer fin surfaceof the second fin section. This will mean that when in normal use on asurfboard, water will preferentially enter the opening on thesubstantially flat outer fin surface, pass through the passage, and exitthrough the opening on the curved outer fin surface. A passage and anopening to a passage through the second fin section is preferably notround or another shape that would cause water passing through thepassage to form a vortex. The openings and passages may be created fromdrilling or cutting holes or perforations through the second fin sectionor from the shape of a mould used to make the fin section.

An adjustable dual fin according to the third aspect of the invention ispreferably mounted in the position of a side fin on a surfboard wherein:

-   -   the fin section and second fin section comprise flat foils        having a substantially flat outer fin surface facing the centre        line or stringer of the surfboard, and a curved outer fin        surface facing the adjacent rail of the surfboard;    -   the fin section is in a position closer to the adjacent rail of        the surfboard than the second fin section; and    -   the leading edge of the fin section is positioned closer to the        front of the board than the leading edge of the second fin        section.

Two or more adjustable dual fins according to the third aspect of theinvention may be mounted to a surfboard.

In a preferred embodiment, the second fin section comprises at least onepassage comprising an opening on the substantially flat outer finsurface, and an opening on the curved outer fin surface of the secondfin section through which water can pass. When the adjustable dual finof the third aspect of the invention is mounted to a surfboard which ismoving in a substantially forward direction through water during normaluse, the at least one passage in the second fin section is preferablyconfigured to:

-   -   enable water to enter an opening on the substantially flat outer        fin surface of the second fin section, pass through the passage,        and exit through an opening on the curved outer fin surface in a        location between the trailing edge of the second fin section and        the position of the minimum distance between the fin section and        the second fin section; and    -   substantially prevent water passing in the reverse direction        through the passage.

The openings preferably comprise holes or perforations on the surface ofthe substantially flat and curved outer fin surfaces of the second finsection through which water can enter and exit, respectively.Preferably, the opening on the substantially flat outer fin surface ofthe second fin section is positioned closer to the leading edge than theopening on the curved outer fin surface.

In an alternative embodiment of the third aspect of the adjustable dualfin of the invention, both the fin section and the second fin sectionare attached to the base. The fin section may be an adjustable finaccording to either the first aspect or second aspect of the invention.The second fin section may be an adjustable fin according to either thefirst aspect or second aspect of the invention.

The second fin section may be the same size or a different size to thefin section. The second fin section may have a different fin template tothe fin section. Preferably, the size and template of the second finsection is similar or the same as the size and template of the finsection.

Mounting Means

The mounting means for an adjustable fin of the invention as hereindescribed may comprise a variety of means known for mounting orattaching a fin to a surfboard or another board.

In a preferred embodiment, the mounting means comprises one or moremounting blocks for attaching to one or more surfboard fin plugs and/orfin boxes. The one or more mounting blocks are preferably compatiblewith commercially available fin plug and/or fin box systems. Preferably,the one or more mounting blocks can be mounted to commercially availableFCS® fin plugs and/or Futures® fin boxes.

In another preferred embodiment, the mounting means comprises a baseattachment surface and an adhesive wherein the adhesive directly andfixedly secures the base attachment surface to the outer bottom surfaceof the surfboard. The adhesive is preferably Araldite® or another epoxyor non-latex construction silicone adhesive that can maintain anadhesive connection between an adjustable fin of the invention and asurfboard or another board, particularly when exposed to water.Preferably, one or more screws additionally secure the adhered baseattachment surface to the surfboard. Said screws are preferably placedin front of the leading edge of the adjustable fin and adjacent to eachouter fin surface. The screws can preferably be turned with a hex orAllen key and screw plugs, for example, plastic screw plugs, and may bepre-set in the surfboard into which the screws can be driven andembedded to secure the base of the adjustable fin to the surfboard.Alternatively, the base attachment surface may be ‘fiberglassed’ ontothe surfboard using traditional ‘glassing’ methods known in the art. Forexample, comprising placing ‘rovings’ around the outer edge or border ofthe base attachment surface.

The base attachment surface may also be used to attach a non-adjustablefin to a surfboard, for example a non-adjustable fin with a removablefin section.

Adjustment Indicators

Means for showing the user the position of the fin section relative tothe base are also within the scope of the invention. Such means mayinclude adjustment indicators, markings or numbering on the fin section,transparent portions of the fin section, or a combination of these, assome non-limiting examples. These means would, for example, enable auser to determine whether two or more adjustable fins mounted as sidefins on a board have been adjusted equally. In another example, a usercould identify by these means the position of a fin section relative toits base when an adjustable fin of the invention is mounted to a board,without having to manipulate or even touch the adjustable fin.

Elevated Fin Section

In an embodiment of any of the first, second, or third aspects of theinvention as herein described, the underside surface of the fin sectionabuts or aligns flush to the outer surface of a surfboard the adjustablefin is mounted to.

In another embodiment of any of the first, second or third aspects ofthe invention as herein described, the adjustable fin comprises anextended base which forms a gap between the underside surface of the finsection and the outer surface of a surfboard on which it is mounted. Thelength of the gap between the underside surface of the fin section andthe outer surface of the surfboard is preferably between approximately 5mm and 25 mm. The length of the gap is more preferably approximatelybetween approximately 10 mm and 20 mm. The length of the gap is morepreferably approximately 15 mm. Without wanting to be limited by any onetheory, a benefit of elevating a fin section from the outer surface of asurfboard on which it is mounted is to reduce drag, when compared to afin section which abuts or aligns flush with the outer surface of asurfboard.

Board Type

The adjustable fin of any of the first, second or third aspects of theinvention as herein described may be mounted to any one of the boards inthe group comprising: surfboard, shortboard, kneeboard, longboard,minimal, soft board, kiteboard or a board used for kite surfing, windsurfer, stand up paddleboard, wakeboard, rescue board, bodyboard, oranother board used in surface water sports or activities. Referenceherein to a surfboard can also include reference to any one of theseother boards.

Fin Arrangement

More than one adjustable fin according to any of the aspects andembodiments of the invention as described herein may be mounted to asurfboard. For example, a thruster fin setup on a surfboard may compriseup to three adjustable fins of the invention as described herein. Insome other non-limiting examples, other arrangements may include:

-   -   Three adjustable fins according to the first aspect of the        invention wherein the two side fins are flat foils and the three        adjustable fins are in a ‘thruster’ arrangement;    -   Three adjustable fins according to the second aspect of the        invention wherein the two side fins are flat foils and the three        adjustable fins are in a ‘thruster’ arrangement;    -   Two adjustable fins according to embodiments of the first or        second aspect of the invention which are flat foils, and a        non-adjustable centre fin;    -   An adjustable centre fin according to embodiments of the first        or second aspects of the invention, and two non-adjustable side        fin flat foils in a ‘thruster’ or another arrangement;    -   An adjustable centre fin according to an embodiment of the first        or second aspect of the invention, and two adjustable dual side        fins according to an embodiment of the third aspect of the        invention;    -   Adjustable side fins according to embodiments of the first or        second aspects of the invention, and a dual centre fin according        to an embodiment of the third aspect of the invention; or    -   Another possible combination.

Therefore, various combinations are possible for using adjustable finsof the invention exclusively, or in combination with non-adjustable orother types of fins on a surfboard.

Process for Mounting a Fin of the Invention

The present invention further provides a process of mounting to asurfboard or another board, an adjustable fin of the invention as hereindescribed. The present invention also provides a process of mounting anadjustable fin of the invention to a surfboard by mounting theadjustable fin using a mounting means as described herein.

Process for Manufacturing a Fin of the Invention

The present invention also provides a process of manufacturing anadjustable fin of the invention as described herein. The adjustable finof the invention is preferably constructed from common materials used tomake surfboard fins. In one embodiment of the invention, part or all ofthe base is constructed from a metal or a metal alloy. This metal ispreferably strong, light weight, and incapable of rusting or significantcorrosion. In one example, the metal is aluminium. The fin section maybe formed from two halves joined together.

Similarly to the large number of different fins currently available formounting to a surfboard or another type of board described herein, anadjustable fin of the invention can comprise a variety of different:shapes or templates or even cants; outer fin surface shapes or features;sizes; types of foils; colours; materials from which the fin section isconstructed; rakes; depths; widths; cants; cut-outs; and other designsand extensions including channels, ‘tunnels’ and ‘wings’, amongstothers. In this regard, a user can select and mount an adjustable fin ofthe invention to a board with attributes that is desired by the user orsuitable for the user's requirements and appropriate for the board theadjustable fin or fins are mounted on.

In developing the present invention, the inventor addressed many issuesthat have prevented successful uptake of adjustable fin systems bysurfers and other board riders.

A first benefit is that no tools are required to adjust the position ofthe adjustable fin on the surfboard. This means that a surfer or anotherboard rider can easily adjust the position of one or more adjustablefins of the invention on their board without leaving the water. Thisallows the ‘fine tuning’ of their board to adjust to a much greaterrange of swell sizes and conditions without paddling in to the beach toswap fins and/or surfboards, and no need for tools or equipment.

A second benefit is that the adjustable fin of the invention canincorporate mounting blocks that attach to existing fin plug and fin boxarrangements such as FCS® fin plugs or Futures® fin boxes. As a result,surfers and other board riders do not have to purchase a new boardhaving a specific fin plug or box arrangement but can use one or moreadjustable fins of the invention in their current boards, and withoutany modifications to their boards.

The adjustable fin according to an embodiment of the third aspect of theinvention provides a third benefit of directing thrust in a directionsubstantially towards the front of the board with an aim of increasingboard speed on a wave.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1. are illustrations showing oblique views of an exploded (A) andassembled (B) embodiment of the first aspect of the adjustable fin ofthe invention. Mount comprises mounting blocks which attach to FCS® finplugs.

FIG. 2. are illustrations showing a top view (A), oblique view (B), sideview (C) and front view (D) and the internal mechanism of an embodimentof the first aspect of the adjustable fin of the invention. Mountcomprises mounting blocks which attach to FCS® fin plugs.

FIG. 3. are illustrations showing oblique views of an explodedembodiment of the first aspect of the adjustable fin of the invention(A) and when mounted to a surfboard (B). Mount comprises a baseattachment surface and an adhesive.

FIG. 4. are illustrations showing side view cross sections of anembodiment of the second aspect of the adjustable fin of the inventionwith the base in the (A) front position, (B) during adjustment betweenpositions, and (C) back position, relative to the fin section. Mountcomprises mounting blocks which attach to FCS® fin plugs.

FIG. 5. are illustrations showing a side view cross section and a topview cut-away cross section of one half of a fin section of anembodiment of the second aspect of the adjustable fin of the invention.

FIG. 6. are illustrations showing a side view cross section and a topview cut-away cross section of the other half of the fin section of FIG.5.

FIG. 7. are illustrations with measurements (in mm) of a front, side andpartial bottom view of an embodiment of the base of the second aspect ofthe adjustable fin the invention. Mount comprises mounting blocks whichattach to FCS® fin plugs.

FIG. 8. are illustrations with measurements (in mm) of a front, side andpartial bottom view of an alternative embodiment to FIG. 7 of the baseof the second aspect of the adjustable fin of the invention. Mountcomprises mounting blocks which attach to FCS® fin plugs.

FIG. 9. (A) is a photograph of the side view of half a fin section and abase as illustrated in FIG. 4(C); (B) is a photograph of the side viewof half a fin section and a base as illustrated in FIG. 4(A); (C) is aphotograph of an end view of an embodiment of the second aspect of theadjustable fin of the invention showing the underside surface of the finsection with opening to the internal cavity, and the base. Mountcomprises mounting blocks which attach to FCS® fin plugs.

FIG. 10. are illustrations showing a side view (A), the opposing sideview (B), front view (C) and top view (D) of an embodiment of the thirdaspect of the adjustable dual fin of the invention. Mount comprisesmounting blocks which attach to FCS® fin plugs.

FIG. 11. are illustrations showing an oblique view (A), blueprint of theoblique view (B), side view (C), blueprint of the side view (D), and anexploded oblique view (E) of an embodiment of the third aspect of theadjustable dual fin of the invention. Mount comprises mounting blockswhich attach to FCS® fin plugs.

FIG. 12. are illustrations showing side, front, and bottom views of anembodiment of the base of the third aspect of the adjustable dual fin ofthe invention. Mount comprises mounting blocks which attach to FCS® finplugs.

FIG. 13. are illustrations showing oblique view (A), oblique explodedview (B), and (clockwise from top left) top, side, oblique and frontview (C) of adjustable fins of the invention mounted by a baseattachment surface and an adhesive to a surfboard, with adjustable dualfins of an embodiment of the third aspect of the invention mounted asside fins, and an adjustable fin of an embodiment of the first aspect ofthe invention mounted as the centre fin.

DESCRIPTION OF PREFERRED EMBODIMENTS

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is to be understood that the inventionincludes all such variations and modifications. The invention alsoincludes all of the steps, features, compositions and compounds referredto or indicated in the specification, individually or collectively andany and all combinations or any two or more of the steps or features.

The present invention is not to be limited in scope by the specificembodiments described herein, which are intended for the purpose ofexemplification only. Functionally equivalent products, compositions andmethods are clearly within the scope of the invention as describedherein.

Throughout this specification, unless the context requires otherwise,the word “comprise”, or variations such as “comprises” or “comprising”,will be understood to imply the inclusion of a stated integer or groupof integers but not the exclusion of any other integer or group ofintegers.

Other definitions for selected terms used herein may be found within thedetailed description of the invention and apply throughout. Unlessotherwise defined, all other scientific and technical terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which the invention belongs.

Features of the invention will now be discussed with reference to thefollowing preferred embodiments.

First Aspect of the Invention

A preferred embodiment of the first aspect of the adjustable fin of theinvention is shown in FIG. 1. FIG. 1A illustrates an exploded view (andFIG. 1B an assembled view) wherein the fin section 100 has a leadingedge 102 and a trailing edge 104 and outer fin surfaces 106 of whichonly one is visible in FIGS. 1A and 1B.

The base 200 comprises a mount 214 comprising two mounting blocks 202which are compatible with the existing commercially available FCS® finplugs fitted to a majority of existing surfboards. When the adjustablefin is mounted on to a surfboard, the mounting blocks 202 are securedwithin FCS® fin plugs and the underside surface 108 of the fin section100 and bottom surface 204 of the base abut, i.e. align with the bottomsurface of the surfboard.

The base 200 comprises a insert member 206 which extends in a directioncontrary to that of the mounting blocks 202. The insert member 206comprises a planar surface with a hole 208 cut out. The hole 208 isshaped to comprise teeth 210 and valleys 212.

The fin section 100 comprises a lock 110 which is shown in FIG. 1Adisassembled into three components, one component comprising the button112 of the lock 110, another component comprising a button support 116,and the other component comprising a button support pin 118 thatconnects the button support 116 to the button 112. FIG. 1B shows thatthe button 112 on the assembled fin lies flush to the outer fin surface106. The underside of the button 112 comprises a slot 114 which when thebutton 112 is depressed on the assembled adjustable fin, the slot 114aligns with the teeth 210 enabling the teeth 210 which have a widththinner than the width of the slot 114, to pass through the slot 114.The button 112 is biased towards releasably coupling the lock 110 to theinsert member 206, and lying flush to the outer fin surface 106.

FIG. 2 illustrates the internal mechanism and interaction between finsection 100 and base 200 when this preferred embodiment of the firstaspect of the adjustable fin of the invention is assembled.

In FIG. 2, the lock 110 is releasably coupled in a locking positionformed by a valley 212 in the hole 208 of the insert member 206. Theinternal cavity 120 in the fin section 100 is configured to enable theinsert member 206 to slidably move by manual force in a directiontowards the trailing edge 104. This can take place after the lock 110 isuncoupled from the insert member 206 when the button 112 is depressed bymanual force and the slot in the button 112 is aligned with the teeth210 allowing the teeth 210 to pass through the slot of the button 112.When the lock 110 is in alignment with another locking position, forexample, formed by a second valley 220, release of the button 112 willmove the slot of the button 112 out of alignment with the teeth 210 andthe teeth 210 will no longer be able to pass through the slot of thebutton 112. As a result, the lock 110 will be restrained in the lockingposition formed by the second valley 220 and therefore releasablycoupled to the insert member 206.

FIG. 3A shows an illustration of an embodiment of the first aspect ofthe adjustable fin of the invention with a mount 232 on the base 200which comprises a base attachment surface 230 to which an adhesive and,in some non-limiting examples, screws, are used to attach the adjustablefin to a surfboard (FIG. 3B).

Second Aspect of the Invention

An embodiment of the second aspect of the adjustable fin of theinvention is shown in FIG. 4 with the fin section 300 in three differentpositions relative to the base 400. The base 400 comprises a mount 422comprising a front mounting block 410 and a rear mounting block 420which can attach to existing available FCS® fin plugs. The base 400 alsocomprises a planar member 430, and attached to which is a flange 440which extends in a direction perpendicular to the planar member 430. Thefin section 300 comprises a leading edge 310 and a trailing edge 320,and an underside surface 330 which abuts the base and outer surface of asurfboard to which it is mounted on. The cross sections through thecentre of the adjustable fin from leading edge 310 to trailing edge 320of the fin section 300 show the internal cavity 340 comprising anopening 350 on the underside surface through which the planar member 430can enter and be housed by the internal cavity 340.

As shown in the three cross sections, the internal cavity 340 isconfigured to allow slidable movement of the base 400 towards theleading edge 310 and a ‘front’ position, or towards the trailing edge320 and a ‘rear’ position upon application of sufficient manual force onthe fin section 300 in opposition to the base 400.

This embodiment of the adjustable fin of the invention further comprisesfixing teeth 450 at the end of the planar member 430 furthest from themounting blocks 410, 420. Recesses 360 in the internal cavity 340 areable to receive the teeth 450 on the insert member to assist to restrainmovement of the insert member in the internal cavity 340. When applyingsufficient manual force to adjust this embodiment of the adjustable fin,the application of sufficient manual force will further comprisemovement of the fin section 300 in a direction away from the base 400,against the elastic pressure of the resiliently deformable material, todislocate the one or more teeth 450 from the recesses 360 to enableslidable movement of the planar member 430 within the internal cavity340, and the flange 440 within the channel as shown in the centre crosssection. As the teeth 450 are positioned at the end of the planar member430 in closest proximity to the trailing edge 320 of the fin section300, the application of sufficient manual force will further comprisemovement of the fin section 300 in a direction away from the base 400 atthe leading edge 310 or trailing edge 320 of the fin section 300. Toprovide for this movement of fin section 300 away from the base 400 todislocate the teeth 450, the flange 440 is preferably curved at each oneor both ends.

An embodiment of the second aspect of the adjustable fin of theinvention is shown in FIG. 5. The fin section 300 comprises a channel370 for housing an extension, and preferably a flange, wherein thechannel 370 contains a resiliently deformable material 372. An extensionsuch as a flange is situated in the gap 374 between the resilientlydeformable material 372 and the upper wall 376 of the channel 370. Theresiliently deformable material 372 forces the flange against the upperwall 376 of the channel 370 to restrict movement of the base relative tothe fin section 300. Measurements for the embodiment of the adjustablefin in FIG. 5 are shown (in mm).

The other half of the fin section of FIG. 5 is shown in FIG. 6. Thishalf of the fin section 300 in FIG. 6 shows the outline of the internalcavity 340 and measurements for this embodiment of the adjustable finare shown (in mm).

FIGS. 7 and 8 show two alternative versions of bases for embodiments ofthe second aspect of the adjustable fin of the invention withmeasurements in mm. The bases comprise mounting blocks which can attachto existing available FCS® fin plugs.

The photographs in FIG. 9A and FIG. 9B show cross sections ofembodiments of a fin section and a base as illustrated in FIG. 4A andFIG. 4B, respectively. The photograph in FIG. 9C shows an embodiment ofthe second aspect of the adjustable fin of the invention with theunderside surface of the fin section and the planar member of baseprojecting from the internal cavity. The bases comprise mounting blockswhich can attach to existing available FCS® fin plugs.

Third Aspect of the Invention

In an embodiment of the third aspect of the present invention, anadjustable dual fin is shown in FIG. 10. The adjustable dual fincomprises the adjustable fin of the first aspect of the invention with afin section 500 and a base 600, wherein a second fin section 550 isattached to the fin section 500 by five ribs 510 of different lengths.Both the fin section 500 and the second fin section 550 are flat foilswith substantially flat outer fin surfaces on one side and curved outerfin surfaces on the other side. The leading edge of the fin section 500is positioned forward of the leading edge of the second fin section.Leading edge passages 552 and trailing edge passages 554 through thesecond fin section 550 are angled towards the curved outer fin surfacewhich forces water to pass through the passage and into the gap betweenthe fin section 500 and second fin section 550. The embodiment furthercomprises an extended base member 610 such that when the adjustable dualfin is mounted on a surfboard, there is a gap between the outer surfaceof the surfboard and the underside surfaces of the fin section 500 andsecond fin section 550. The bases of the embodiment comprise mountingblocks which can attach to existing available FCS® fin plugs.

Without wanting to be limited by any one theory, it is believed thatthis embodiment of the adjustable dual fin of the third aspect of theinvention provides a benefit of increased thrust and therefore speed ina direction substantially towards the front of a surfboard it is mountedto when in normal use, for the following reasons.

As shown in the embodiment in FIG. 10, the distance between the flatouter fin surface 520 of the fin section 500, and the curved outer finsurface 560 of the second fin section 550 is nearest at the peak 562 ofthe curved outer fin surface 560 of the second fin section 550. Thisdistance is preferably between approximately 0.1 mm and 5 mm, morepreferably between approximately 0.25 mm and 1.5 mm, and even morepreferably approximately 1 mm. The proximity and position of the finsection 500 and the second fin section 550 forms a V-shaped channel 564between the peak 562 and the leading edge 566 of the fin section 500 andthe leading edge 568 of the second fin section 550, the V-shaped channel564 extending along the curved length of the fin sections to their tips570. On the other side of the peak 562 is a rear chamber 572 formedbetween the peak 562 and the trailing edge 574 of the fin section 500and the trailing edge 576 of the second fin section 550.

During normal use when mounted on a surfboard, water passes into theV-shaped channel but only a small amount of this water can pass betweenthe thin gap between the fin section and the second fin section. Themajority of the water is forced along the length of the V-shaped channeltowards the tip of the fin sections at a higher velocity than the normalspeed that water is passing the fin sections. This higher velocity isgenerated due to the higher pressure behind the water forced into thechannel than the pressure of the water in front of the water leaving thechannel adjacent to the tips of the fin sections according to Newton's2nd law. In accordance with Bernoulli's principle, the increase in thevelocity of the water occurs simultaneously with a decrease in pressure.Therefore, a region of low pressure is created in this V-shaped channel.

Conversely, some water passes through the thin gap between the finsection and the second fin section, and passages direct water throughthe second fin section from the side of the substantially flat outer finsurface into the rear chamber. The effect of forcing all of this waterinto the limited space of the rear chamber results in the creation of aregion of high pressure.

The pressure differential between the area of low pressure in theV-shaped channel and the area of high pressure in the rear chamberresults in a lift force acting perpendicular to the direction of thefluid flow in the V-shaped channel. That is, in a direction towards thefront of the fin on a slight downward angle. The thrust provided by thislift force acts to increase the overall speed of the fins in thisdirection, and therefore, the board through the water.

FIGS. 11B and 11D show the internal structure and mechanism fromdifferent views of the same embodiment of the third aspect of theadjustable dual fin of the invention shown in FIGS. 11A and 11C,respectively. FIG. 11 E shows an exploded view of the same embodiment.The bases comprise mounting blocks which can attach to existingavailable FCS® fin plugs.

An alternative embodiment of the base of an adjustable dual fin of theinvention is shown in FIG. 12. The base comprising two members andextensions which can be housed within the internal cavities of twoindependent fin sections that are adjustable according to the secondaspect of the invention as described herein. Measurements are shown (inmm). The base comprises mounting blocks which can attach to existingavailable FCS® fin plugs.

Embodiments of the adjustable fin and adjustable dual fin of theinvention which have been mounted onto a surfboard are shown in FIG. 13.The mount for these embodiments comprises a base attachment surfacewhich attaches to the surfboard by an adhesive. An adjustable finaccording to the first aspect of the invention is mounted to thesurfboard as a centre fin. Mounted to the surfboard as side fins areadjustable dual fins according to embodiments of the third aspect of theinvention.

1-25. (cancelled)
 26. A dual fin for use on a surfboard, the dual fincomprising: a fin section comprising two outer fin surfaces which meetat a leading edge and a trailing edge; a second fin section comprisingtwo outer fin surfaces which meet at a leading edge and a trailing edge,and are substantially parallel to the outer fin surfaces of the finsection; a base, comprising a mount for attaching the dual fin to asurfboard, wherein an outer fin surface of the fin section is positionedadjacent to and facing an outer fin surface of the second fin section.27. A dual fin according to claim 26, wherein the second fin section isattached to the first fin section by one or more attachments.
 28. A dualfin according to claim 27, wherein the one or more attachments compriseone or more ribs.
 29. A dual fin according to claim 27, wherein the oneor more attachments preserve a minimum distance between the fin sectionand the second fin section of between approximately 0.25 mm and 1.5 mm.30. The dual fin according to claim 26, wherein the fin sectioncomprises a flat foil having a flat outer fin surface, and a curvedouter fin surface.
 31. The dual fin according to claim 30, wherein thesecond fin section comprises a flat foil having a flat outer fin surfacethat faces the same direction as the flat outer fin surface of the finsection, and a curved outer fin surface.
 32. The dual fin according toclaim 31, wherein the flat outer fin surface of the fin section facesthe curved outer fin surface of the second fin section.
 33. The dual finaccording to claim 26, wherein the second fin section is positionedparallel to the fin section and offset such that the leading edge of thesecond fin section is not aligned with the leading edge of the finsection.
 34. The dual fin according to claim 26, comprising a passagethrough the second fin section through which water can pass, wherein thepassage comprises an opening on each outer fin surface of the second finsection through which water can enter and/or exit.
 35. The dual finaccording to claim 34, comprising a passage through the second finsection through which water can pass, wherein: the passage comprises anopening on the flat outer fin surface, and an opening on the curvedouter fin surface, and the opening on the curved outer fin surface islocated between the trailing edge of the second fin section and theminimum distance between the fin section and the second fin section; theopening of the passage on the flat outer fin surface is located closerto the leading edge of the second fin section than the opening of thepassage on the curved outer fin surface of the second fin section; andwater can enter the opening on the flat outer fin surface, pass throughthe passage, and exit through the opening on the curved outer finsurface.
 36. The dual fin according to claim 35, wherein water can enterthe opening of the passage on the flat outer fin surface, pass throughthe passage, and exit through the opening of the passage on the curvedouter fin surface.
 37. The dual fin according to claim 26, wherein theone or more mounts are mounting blocks capable of attaching tocommercially available fin plug and fin box systems.
 38. The dual finaccording to claim 26, wherein the mount comprises a base attachmentsurface and an adhesive for mounting the dual fin to an outer surface ofa surfboard.
 39. The dual fin according to claim 26, comprising anextended base, wherein when the dual fin is mounted on a surfboard, theextended base forms a gap between the outer surface of the surfboard andthe underside surfaces of the fin section and second fin section. 40.The dual fin according to claim 39, wherein the length of the gap isbetween approximately 10 mm and 20 mm.
 41. The dual fin according toclaim 26, for mounting to any one of the boards in the group comprising:surfboard, shortboard, kneeboard, longboard, minimal, soft board,kiteboard, wind surfer, stand up paddleboard, wakeboard, rescue board,bodyboard, or another board used in surface water sports or activities.42. A process comprising the step of mounting a dual fin according toclaim 26, to any one of the boards in the group comprising: a surfboard,a shortboard, a kneeboard, a longboard, a minimal, soft board, akiteboard, a wind surfer, a stand up paddleboard, a wakeboard, a rescueboard, a bodyboard, or another board used in surface water sports oractivities.